0:00:04 > 0:00:07The most iconic of all the big cats.
0:00:12 > 0:00:17Lions have attracted our attention throughout history.
0:00:18 > 0:00:20I'm Jonathan Scott and for me,
0:00:20 > 0:00:26the lion's the main reason I came to Africa over three decades ago.
0:00:29 > 0:00:33Human beings have painted, sculpted and photographed this big cat
0:00:33 > 0:00:36perhaps more than any other.
0:00:39 > 0:00:46Across the world and across our cultures, we've recorded the lion's story in considerable detail.
0:00:46 > 0:00:49But, for how much longer can their story continue?
0:00:49 > 0:00:53With perhaps as few as 25,000 lions left in Africa,
0:00:53 > 0:00:55could this be the final chapter?
0:00:58 > 0:01:02For over 30 years, the world's leading lion scientist Craig Packer
0:01:02 > 0:01:05has headed the Serengeti Lion Project.
0:01:05 > 0:01:09And he has a stark warning.
0:01:09 > 0:01:11The lion is in trouble.
0:01:11 > 0:01:17In the last dozen years, the lion population has declined anywhere between 20 and 50%.
0:01:18 > 0:01:23We're reaching a threshold where we might pass the point of no return.
0:01:25 > 0:01:29The lion is the uniquely social cat.
0:01:29 > 0:01:33The only one to live in prides.
0:01:34 > 0:01:38I want to understand what role it could be playing in their decline.
0:01:41 > 0:01:47Using the latest scientific research and by watching my pride's trials and tribulations,
0:01:47 > 0:01:51I want to reveal The Truth About Lions.
0:02:31 > 0:02:37From a balloon, the sight of Kenya's world-famous Maasai Mara Game Reserve is breathtaking.
0:02:45 > 0:02:49And it's just the northern tip of a vast, wild ecosystem
0:02:49 > 0:02:51of 25,000 square kilometres
0:02:51 > 0:02:57stretching all the way south into Serengeti National Park.
0:03:04 > 0:03:06I've spent much of my adult life here,
0:03:06 > 0:03:12recording the fascinating stories of its lions, leopards and cheetahs.
0:03:13 > 0:03:19One area in particular has always stood out for me as a hot-spot for wildlife -
0:03:19 > 0:03:22the Musiara Marsh.
0:03:23 > 0:03:28It's home to a family of lions I've come to know intimately...
0:03:28 > 0:03:30the Marsh pride.
0:03:37 > 0:03:40The fact that I've been able to watch this pride for so long
0:03:40 > 0:03:44is witness to what a great territory they have within this landscape
0:03:44 > 0:03:46and is the reason for their continued success,
0:03:46 > 0:03:50and right now we've got hundreds of thousands of wildebeest
0:03:50 > 0:03:51streaming into the area,
0:03:51 > 0:03:54so it's just an amazing place to be a lion.
0:03:56 > 0:03:59September.
0:03:59 > 0:04:03The time for the 28 members of the Marsh pride to feast.
0:04:36 > 0:04:41Their tolerance of human observers allows us to film them
0:04:41 > 0:04:43even under the cover of darkness.
0:04:47 > 0:04:50This is a sight that can only be seen with lions.
0:04:55 > 0:04:58A whole family of related animals,
0:04:58 > 0:05:01all part of the same pride all feeding together.
0:05:05 > 0:05:08This family living, this social way of life,
0:05:08 > 0:05:11makes lions the most conspicuous, the most often seen,
0:05:11 > 0:05:13of all the world's big cats.
0:05:16 > 0:05:20Far more regularly sighted than the traditionally secretive leopard.
0:05:22 > 0:05:29Yet there are, perhaps, 20 times as many wild leopards left on Earth as there are lions.
0:05:46 > 0:05:49The lion's familiarity masks a dark truth.
0:05:55 > 0:06:00A truth brought home to me when I met the world's foremost lion scientist Craig Packer
0:06:00 > 0:06:03in Tanzania, by a rather unusual slide-show.
0:06:08 > 0:06:11This is amongst the oldest art in the world.
0:06:11 > 0:06:16Projected on a rock, these slides, of 35,000-year-old cave paintings
0:06:16 > 0:06:21from Southern France, depict lions in incredible detail
0:06:21 > 0:06:25and show that humans have had a surprisingly close relationship
0:06:25 > 0:06:28with this particular cat for millennia.
0:06:28 > 0:06:32When I first saw these paintings I was profoundly moved.
0:06:32 > 0:06:35It gave me chills.
0:06:35 > 0:06:41And to see these paintings by fellow lionologists from 35,000 years ago
0:06:41 > 0:06:44made me realise that maybe we're not so eccentric
0:06:44 > 0:06:49watching these animals, that this is something that's very deep in our nature.
0:06:51 > 0:06:55But the truth they reveal is just how widespread lions once were.
0:06:57 > 0:07:02The lion had a representation across Europe.
0:07:02 > 0:07:05It went across Alaska, across Asia.
0:07:05 > 0:07:11At one point the lion was the most widely-distributed mammal across the entire planet.
0:07:15 > 0:07:19Today, lions are a species in frightening decline,
0:07:19 > 0:07:24restricted now almost exclusively to Africa.
0:07:27 > 0:07:31Craig and his team at the Serengeti Lion Project have spent
0:07:31 > 0:07:34over 30 years investigating the lion,
0:07:34 > 0:07:38gaining a unique scientific insight into its world.
0:07:39 > 0:07:44A world which Craig is only too aware is shrinking.
0:07:44 > 0:07:48If you look at where the last remaining large populations of
0:07:48 > 0:07:53lions are found, Kruger Park in South Africa, the Okavango in Botswana,
0:07:53 > 0:07:56and then four places here in Tanzania
0:07:57 > 0:08:02and between those half-dozen populations, there's probably half,
0:08:02 > 0:08:06at least, maybe more, of all the lions left in Africa.
0:08:18 > 0:08:23The Marsh pride, my lions, are part of one of these populations -
0:08:23 > 0:08:25the Serengeti Mara population.
0:08:28 > 0:08:32To understand the risks they face and the causes of the lion's decline
0:08:32 > 0:08:36I need to see life from a lion's perspective.
0:08:38 > 0:08:42The unique perspective of the only social-living cat.
0:08:51 > 0:08:54Lions need to be together.
0:08:54 > 0:08:59The lion's historic success shows that pride-living has been a good strategy.
0:09:02 > 0:09:06Now, through watching the Marsh pride with fresh eyes
0:09:06 > 0:09:08and armed with Craig's wider research,
0:09:08 > 0:09:11I want to discover if the lion's sociality
0:09:11 > 0:09:13may be contributing to its downfall.
0:09:19 > 0:09:25Having studied them closely for many years, I know them all as individuals.
0:09:26 > 0:09:30Right now the pride consists of a core of adult females -
0:09:30 > 0:09:33White-Eye, Bibi and Lispy.
0:09:35 > 0:09:37There's some new arrivals who,
0:09:37 > 0:09:40at just three months old, are the pride's future.
0:09:44 > 0:09:46And finally the two pride males,
0:09:46 > 0:09:49who have been with this pride for almost three years.
0:09:53 > 0:09:57But whose fortunes, right now, differ widely.
0:10:02 > 0:10:08Romeo is about nine or ten years old. He's a male in his prime.
0:10:08 > 0:10:10Marking ownership of the territory
0:10:10 > 0:10:15and obviously showing interest towards in-season females.
0:10:17 > 0:10:20Looking to father more offspring.
0:10:26 > 0:10:30His buddy, the other pride male, is Clawed...
0:10:33 > 0:10:36..who at 12 years old is showing his age.
0:10:40 > 0:10:44At best, Clawed could perhaps reach 14 years old.
0:10:44 > 0:10:47But that's looking increasingly unlikely.
0:10:51 > 0:10:54He's obviously in poor condition.
0:10:55 > 0:10:57His teeth are worn down
0:10:57 > 0:11:01and he's struggling to get enough food at times.
0:11:05 > 0:11:09Yet, without him, Romeo would find it almost impossible
0:11:09 > 0:11:13to hold onto the pride and raise any more offspring.
0:11:18 > 0:11:21In the wild, males die much younger than females,
0:11:21 > 0:11:23mostly through violent encounters with other males -
0:11:23 > 0:11:27males who want to take over their territory.
0:11:31 > 0:11:34Clawed is at risk,
0:11:34 > 0:11:37even from the lion's own prey.
0:11:55 > 0:11:58Buffalo are big animals.
0:11:58 > 0:12:03At almost 700 kilos, they're over three times the weight of a lion.
0:12:14 > 0:12:21Lions and buffalo are mortal enemies and buffalo will actively chase lions.
0:12:21 > 0:12:25If they discover cubs, or a lion is unable to get out of the way,
0:12:25 > 0:12:27they'll kill them.
0:12:31 > 0:12:35The pride begin to move away, to protect the cubs.
0:12:35 > 0:12:39But, old and weak, Clawed has to try a different tactic.
0:12:48 > 0:12:52Hide and seek initially works well.
0:12:55 > 0:12:59But the buffalo's keen sense of smell eventually prevails.
0:13:03 > 0:13:04Clawed has a bad leg,
0:13:04 > 0:13:09but still manages to muster up enough energy to run for his life.
0:13:18 > 0:13:22He only just manages to reach safety in time.
0:13:31 > 0:13:34Hopefully, the buffalo will lose interest.
0:13:41 > 0:13:46In situations like this, the pride focus on keeping the cubs safe.
0:13:49 > 0:13:52Adult lions must fend for themselves,
0:13:52 > 0:13:55and there's little chance the others will come to Clawed's help.
0:14:14 > 0:14:17Eventually Clawed is able to rejoin the pride.
0:14:21 > 0:14:23He's had a lucky escape.
0:14:25 > 0:14:28I've seen lions killed by buffalo,
0:14:28 > 0:14:32indeed, many lions die as a result of a violent attack.
0:14:32 > 0:14:37Sometimes by buffalo, but more often at the jaws of other lions.
0:14:43 > 0:14:47Clawed is clearly vulnerable not just to attack,
0:14:47 > 0:14:49but also from a more silent threat.
0:14:49 > 0:14:51The threat of disease.
0:14:53 > 0:14:58Most lions die a violent death, but it's very easy to forget the role that disease can play.
0:14:58 > 0:15:01And of course the danger in a social animal such as this
0:15:01 > 0:15:04is that it could spread amongst the whole group.
0:15:07 > 0:15:09Clawed's poor condition
0:15:09 > 0:15:12makes him potentially the most vulnerable to disease.
0:15:14 > 0:15:20Disease is something I've seen affect individual lion prides like the Marsh pride.
0:15:24 > 0:15:28But just how dramatically it can affect whole populations
0:15:28 > 0:15:32is something Craig had a chance to discover in 1994.
0:15:41 > 0:15:47At the beginning of 1994, various people saw lions suddenly
0:15:47 > 0:15:51with really strange disease symptoms that had never been seen before.
0:15:51 > 0:15:55The most famous case was a male who had convulsions,
0:15:55 > 0:15:57like a horrible, horrible seizure.
0:15:59 > 0:16:03Turned out that this animal was infected with canine distemper
0:16:03 > 0:16:08and it infected about 95% of the lions within the Serengeti.
0:16:11 > 0:16:14It devastated prides.
0:16:18 > 0:16:22And was obviously a risk to the whole lion population.
0:16:29 > 0:16:33Canine distemper virus is a disease of the nervous system.
0:16:33 > 0:16:36It more usually affects domestic dogs
0:16:36 > 0:16:40and is closely related to measles in humans.
0:16:40 > 0:16:45But it had been spread into the park by hyenas who regularly move between
0:16:45 > 0:16:49the surrounding rural villages and the park's centre.
0:16:54 > 0:17:01The huge lion deaths in 1994 were followed by a similar event in 2001.
0:17:01 > 0:17:06Initially, it seemed canine distemper virus or CDV was to blame.
0:17:10 > 0:17:15But the project had been keeping blood samples for a number of years, which when analysed
0:17:15 > 0:17:21showed that there had been other outbreaks of CDV that didn't result in any lions dying.
0:17:22 > 0:17:27We've had seven distemper outbreaks over the last 20 years now
0:17:27 > 0:17:31and only two have had that high degree of mortality.
0:17:33 > 0:17:35There was something else going on.
0:17:35 > 0:17:38The team looked again at the two outbreaks that had
0:17:38 > 0:17:43resulted in so many lion deaths and noticed something in common.
0:17:46 > 0:17:50They both occurred at the end of a severe drought.
0:17:52 > 0:17:54The herbivores like wildebeest and buffalo
0:17:54 > 0:18:00struggled to find enough to eat and were themselves weakened by disease.
0:18:02 > 0:18:06The lions suddenly had what seemed like a free lunch
0:18:06 > 0:18:09with this excess of buffalo that were sick and very easy to catch.
0:18:09 > 0:18:12But there's no such thing as a free lunch.
0:18:27 > 0:18:30The buffalo, the lions' preferred prey,
0:18:30 > 0:18:34had many more ticks than usual and those ticks spread
0:18:34 > 0:18:36from the dying buffalo to the lions
0:18:36 > 0:18:40carrying a dangerous malaria-like parasite called babesia.
0:18:42 > 0:18:46Now, babesia in itself is something the lions can ordinarily handle,
0:18:46 > 0:18:51but this was an exceptional dose of babesia, combined with distemper
0:18:51 > 0:18:56and the distemper is like a short, sharp bout of AIDS.
0:18:56 > 0:19:01They're immuno-suppressed, allowing the babesia to overwhelm them and that's actually what killed them.
0:19:04 > 0:19:09Buffalo are the lion's preferred prey precisely because they're large
0:19:09 > 0:19:10and can feed a whole pride.
0:19:13 > 0:19:15But in this instance,
0:19:15 > 0:19:19being social exposed whole prides to disease at once.
0:19:20 > 0:19:24The disease outbreak had a catastrophic effect on the lion population.
0:19:24 > 0:19:28We saw hundreds of losses in the Serengeti, and we saw losses here
0:19:28 > 0:19:30in the Mara in the Marsh pride.
0:19:30 > 0:19:35But what was interesting was, it didn't take that long for the lion population to bounce back again.
0:19:45 > 0:19:49In fact, it only took four years to recover to pre-disease levels.
0:19:55 > 0:20:00This is the flip-side to being social.
0:20:00 > 0:20:04Given the right habitat, lion prides breed very successfully and rapidly.
0:20:15 > 0:20:18But more frequent droughts in the future
0:20:18 > 0:20:21could trigger more regular outbreaks of disease
0:20:21 > 0:20:24and might not allow lion prides time to recover,
0:20:24 > 0:20:29potentially decimating an otherwise healthy lion population.
0:20:31 > 0:20:35The role of climate change in affecting lion numbers
0:20:35 > 0:20:37shouldn't be underestimated.
0:20:41 > 0:20:45The impact of climate change is likely to increase in these kind of areas.
0:20:45 > 0:20:48We'll see more droughts and we'll see more floods
0:20:48 > 0:20:53and that is likely to act as a trigger for these outbreaks of epidemic diseases.
0:20:53 > 0:20:57Now another perhaps surprising way in which climate change can impact
0:20:57 > 0:20:59on the lion population, is in the way they look.
0:21:04 > 0:21:06Male lions have a striking feature
0:21:06 > 0:21:11that marks them out from lionesses and all other big cats.
0:21:13 > 0:21:14The mane.
0:21:20 > 0:21:24It develops during puberty and attains its full glory
0:21:24 > 0:21:27just as the male reaches his reproductive prime.
0:21:28 > 0:21:31But it carries a heavy price tag.
0:21:33 > 0:21:38All mammals need to maintain a constant body temperature
0:21:38 > 0:21:40regardless of their surroundings.
0:21:43 > 0:21:48But male lions like Clawed and Romeo have a problem.
0:21:48 > 0:21:52Their big, bushy manes are like a jumper, one they can't take off.
0:21:56 > 0:22:00Viewed through a thermal camera, the mane's contrasting colour
0:22:00 > 0:22:04shows how much warmer the mane is than the rest of the lion.
0:22:12 > 0:22:17In the hottest parts of Africa, this burden is simply too much to bear.
0:22:19 > 0:22:21And the lions here are different.
0:22:25 > 0:22:30Craig's data clearly shows that male lions growing up in hotter habitats
0:22:30 > 0:22:33tend to grow shorter, thinner and lighter manes
0:22:33 > 0:22:36than those growing up in cooler climes.
0:22:39 > 0:22:43So climate change could eventually alter the lion's look.
0:22:49 > 0:22:54But ultimately, does it matter what colour the mane is?
0:22:55 > 0:22:59And, if they're such a burden, why grow a mane in the first place?
0:23:01 > 0:23:03Craig and his team had a hunch
0:23:03 > 0:23:08that the mane might have a profound meaning in lions' social lives.
0:23:10 > 0:23:13To set about decoding what that meaning might be,
0:23:13 > 0:23:17they enlisted a somewhat surprising research tool.
0:23:17 > 0:23:21We had these dummies constructed and shipped out here,
0:23:21 > 0:23:25where we could present alternatives to the lions.
0:23:25 > 0:23:31So we'd find a wild lion, we'd set out two dummies at a time, with contrasting manes.
0:23:31 > 0:23:36One might be dark, one would be light, or one would be short and one would be long.
0:23:36 > 0:23:38OK, Fabio - you're on!
0:23:41 > 0:23:44And the females clearly preferred the darker manes.
0:23:47 > 0:23:49It turns out that black-maned males,
0:23:49 > 0:23:51they're actually superior males.
0:23:51 > 0:23:54They have higher testosterone levels, they live longer,
0:23:54 > 0:23:57they're more likely to survive from being wounded
0:23:57 > 0:23:59and their cubs have much better survival.
0:23:59 > 0:24:03So a female making a choice would do much better
0:24:03 > 0:24:06to have her children fathered by one of the black-maned males.
0:24:10 > 0:24:15The mane, it turns out, plays a huge part in lion society.
0:24:18 > 0:24:23The ability to grow a big, dark mane is a sign of fitness.
0:24:23 > 0:24:27It's an honest signal that you're strong enough to carry the burden
0:24:27 > 0:24:31of all that extra heat stress - it shows you have good genes.
0:24:33 > 0:24:39And that's why, in nine out of ten cases, lionesses prefer dark-maned males.
0:24:47 > 0:24:52In the Marsh pride, Romeo is the female's favourite right now
0:24:52 > 0:24:54with his dark, luxuriant mane.
0:25:03 > 0:25:06But his mane won't always look so grand.
0:25:11 > 0:25:13The aging Clawed,
0:25:13 > 0:25:16two years older than Romeo, has a less impressive mane.
0:25:21 > 0:25:24But right now, with plenty of food available,
0:25:24 > 0:25:28he's still at least managing to maintain a reasonable head of hair.
0:25:30 > 0:25:34The females don't take too much notice,
0:25:34 > 0:25:37but it's still a powerful signal to other males.
0:25:44 > 0:25:51The mane allows rival males to quickly assess each other's strengths and avoid direct conflict.
0:25:53 > 0:25:58Fights between males often lead to injury and are best avoided.
0:26:22 > 0:26:25Just the sight of Romeo and Clawed together
0:26:25 > 0:26:26will be a powerful deterrent
0:26:26 > 0:26:31to any new males lurking on the edges of Marsh pride territory.
0:26:33 > 0:26:38There's no doubt that the mane plays a significant role in lion society.
0:26:38 > 0:26:42But the very thing that makes them attractive to females
0:26:42 > 0:26:46and wards off other males also puts them at risk.
0:26:58 > 0:27:03In the last century, tens of thousands of lions were killed by big-game hunters.
0:27:11 > 0:27:15And that had an effect on what sorts of lions were being seen.
0:27:17 > 0:27:23When I first arrived in the Mara in the 1970s, it was rare to see those big black-maned lions
0:27:23 > 0:27:29such as Clawed and Romeo, who are so essential to maintaining the integrity of a pride's territory.
0:27:29 > 0:27:36But in 1977, the Kenyan government decided to ban all trophy-hunting and the sale of wildlife products.
0:27:36 > 0:27:40When they did that, the male lion population began to recover again.
0:27:44 > 0:27:50But trophy-hunting still continues in many parts of Africa today, as shown in this simulation.
0:27:57 > 0:28:02In Tanzania, we're the biggest country for lion trophy-hunting in all of Africa,
0:28:02 > 0:28:08and the hunters have access to more than seven times as much land as the national parks.
0:28:14 > 0:28:19This vast amount of hunting land often surrounds protected areas,
0:28:19 > 0:28:24the parks, and acts as a buffer zone between people and wildlife.
0:28:24 > 0:28:31It may seem ironic, but some believe trophy-hunting of lions could play an important role
0:28:31 > 0:28:36in protecting their habitat and ultimately, them as a species.
0:28:38 > 0:28:42The human population is growing at 4% annually in Tanzania,
0:28:42 > 0:28:46so there's increasing pressure to convert the land to agriculture
0:28:46 > 0:28:52and human settlement. Ultimately, it all comes down to money.
0:28:52 > 0:28:55There are many areas in Africa that will never be attractive
0:28:55 > 0:28:59to photo tourism, that do provide lion habitat.
0:28:59 > 0:29:04Trophy-hunting could help justify that set aside, so that the land
0:29:04 > 0:29:07is not converted to agriculture. It's not lost to wildlife.
0:29:10 > 0:29:16But perhaps most important is to recognise the limited amount of revenue
0:29:16 > 0:29:19that so far has been collected from trophy-hunting.
0:29:19 > 0:29:22Shooting a lion is surprisingly inexpensive.
0:29:22 > 0:29:28For North American hunters who might want to shoot big-horned sheep in certain areas of the US,
0:29:28 > 0:29:33they might pay over a 100,000 for the opportunity.
0:29:34 > 0:29:39Lions, as a species, are far less common than big-horned sheep
0:29:39 > 0:29:44and yet a client can go out and get a licence to shoot a lion
0:29:44 > 0:29:47for less than 10,000.
0:29:54 > 0:30:01In Tanzania, tourism to National Parks generates four times more revenue than hunting.
0:30:08 > 0:30:12There's a real danger that if areas set aside for hunting
0:30:12 > 0:30:16can't generate enough income, they'll be converted to human settlement.
0:30:27 > 0:30:31For trophy-hunting of lions to be an effective conservation tool,
0:30:31 > 0:30:36it first needs to generate vastly more income than it does currently.
0:30:45 > 0:30:47GUNSHOT
0:30:53 > 0:30:57Secondly, the choice of lion to kill is critical.
0:30:58 > 0:31:02An adult male with a large impressive mane
0:31:02 > 0:31:06is the most sought-after trophy, like those of Clawed and Romeo.
0:31:08 > 0:31:13It may seem that hunting a lion affects just that one animal.
0:31:13 > 0:31:16But the consequences are much more significant.
0:31:16 > 0:31:21We have to keep in mind that the lion does have a very complex social system.
0:31:21 > 0:31:23Unlike most trophy species
0:31:23 > 0:31:26where the male only meets the female once for mating,
0:31:26 > 0:31:29and has nothing to do with tending to the offspring,
0:31:29 > 0:31:32the pride male is a devoted father.
0:31:32 > 0:31:36He needs to continue to be around until his young are safely raised.
0:31:36 > 0:31:41So if a hunter comes in and removes an adult male from a pride,
0:31:41 > 0:31:46he'll render his offspring and the rest of the pride vulnerable
0:31:46 > 0:31:48to a take over by a new set of males.
0:31:51 > 0:31:55If the new males are coming into a pride while there's still dependent young,
0:31:55 > 0:32:00from the preceding set of males, all hell breaks loose.
0:32:07 > 0:32:10If for instance, Clawed and Romeo were killed now,
0:32:10 > 0:32:13new males would kill all cubs under nine months old
0:32:13 > 0:32:17to bring the females back into season and give themselves a chance
0:32:17 > 0:32:20of raising their own offspring.
0:32:25 > 0:32:29The mothers of the older cubs would move away to protect them
0:32:29 > 0:32:31and the pride would be fractured.
0:32:36 > 0:32:40Regularly removing pride males destroys the stability
0:32:40 > 0:32:43required to successfully raise the next generation.
0:32:47 > 0:32:53The hunting industry has to be a fair player and recognise
0:32:53 > 0:32:57that past practices have been inadequate and it's time for careful oversight,
0:32:57 > 0:33:00this is a very rare and precious species
0:33:00 > 0:33:04that must be hunted in a very careful and sustainable manner.
0:33:08 > 0:33:12The impact of trophy-hunting can be minimised.
0:33:16 > 0:33:21First, it's important to establish the age of the male lion to be shot.
0:33:21 > 0:33:26Something hunters could do by looking closely at their quarry.
0:33:27 > 0:33:30I've been keeping records on the Marsh pride for so long,
0:33:30 > 0:33:34and know the nine sub-adults with the pride are about three years old.
0:33:34 > 0:33:37The reason I know that is that I saw them as young cubs
0:33:37 > 0:33:40when they emerged from the den at about two months old.
0:33:40 > 0:33:46But if I didn't know how old they were, I could use a method developed by Craig and his team
0:33:46 > 0:33:48which relies on the fact that young lions,
0:33:48 > 0:33:51such sub-adults have pink noses till they're four,
0:33:51 > 0:33:55but after that time, and you can just see it here.
0:33:55 > 0:34:00This is a five-year-old lion, black pigment begins to cover the nose.
0:34:00 > 0:34:03So his nose is half-black, half-pink - five years old.
0:34:03 > 0:34:08If you look at this male, a previous pride male, his nose is black.
0:34:08 > 0:34:11He's nearer ten years old and you can see his teeth are worn.
0:34:11 > 0:34:15So, if you don't know the age of a lion, using Craig's method,
0:34:15 > 0:34:17you can get a pretty good estimate.
0:34:19 > 0:34:22The age of a lion is crucial.
0:34:22 > 0:34:27On average, male lions are four years old when they take over a pride
0:34:27 > 0:34:33and remain in control for roughly two years before being evicted by younger rivals.
0:34:35 > 0:34:39Time enough to raise just one group of young.
0:34:43 > 0:34:48Hunting male lions only over six years of age minimises the risk
0:34:48 > 0:34:52of killing males before they've had a chance to breed.
0:34:52 > 0:34:56Or whilst they're a father to young, dependant cubs.
0:34:56 > 0:35:01Clawed and Romeo are both significantly older than six.
0:35:01 > 0:35:07In their time in charge, they've already fathered a group of nine three-year-old lions -
0:35:07 > 0:35:13who are now nearly fully grown - as well as this second group of younger cubs.
0:35:18 > 0:35:22The impact of one, or both of our males demise
0:35:22 > 0:35:26would consign the youngest cubs to a violent death by incoming males.
0:35:28 > 0:35:33It would be tragic, but Clawed and Romeo have already assured their genetic success
0:35:33 > 0:35:36in the raising of their first brood.
0:35:38 > 0:35:41Clawed and Romeo have been pride males here
0:35:41 > 0:35:45for longer than any previous males I've recorded.
0:35:45 > 0:35:48They are literally living on borrowed time.
0:35:53 > 0:35:58New, younger, males are lurking on the edges of Marsh pride territory
0:35:58 > 0:36:02waiting for an opportunity to challenge the holders.
0:36:02 > 0:36:05HE BELLOWS
0:36:11 > 0:36:14Males outside a pride normally don't roar,
0:36:14 > 0:36:17to avoid unnecessary attention.
0:36:17 > 0:36:19HE BELLOWS
0:36:26 > 0:36:32But these two youngsters clearly consider the Marsh pride's territory is theirs for the taking!
0:37:05 > 0:37:11Much of what's happening with the Marsh pride right now is occurring after dark.
0:37:11 > 0:37:15One of the classic sounds of the African night is the sound of lions roaring.
0:37:15 > 0:37:17LIONS ROAR
0:37:21 > 0:37:24SNARLING ROARS
0:37:24 > 0:37:26HE ROARS
0:37:34 > 0:37:38The lion's roar advertises their ownership of a territory.
0:37:38 > 0:37:40HE ROARS
0:37:45 > 0:37:50Work by the Serengeti Lion Project showed that, as a pride roars,
0:37:50 > 0:37:54other lions hearing it can count how many lions are calling.
0:38:01 > 0:38:07The project also showed that the roar is directly related to body size.
0:38:07 > 0:38:09Being up to 50% larger than females,
0:38:09 > 0:38:14the males' roar is louder and deeper than the lionesses'.
0:38:17 > 0:38:22Though Clawed is a shadow of his former self, his continuing ability to roar with the pride
0:38:22 > 0:38:27is helping to keep potential invaders at bay - for now.
0:38:27 > 0:38:31HE ROARS
0:38:42 > 0:38:45Life for all lions is a numbers game.
0:38:45 > 0:38:48Outnumbering the opposition is key to success.
0:38:50 > 0:38:54When there's just one male voice left in the Marsh pride,
0:38:54 > 0:38:57it will be noticed by other males in the area
0:38:57 > 0:39:00and the odds will switch in their favour.
0:39:22 > 0:39:26The Marsh pride's social life is like a feline soap opera.
0:39:33 > 0:39:40But it's clear that, for lions, their unique social lifestyle
0:39:40 > 0:39:46makes for unique pressures from factors such as disease outbreaks and trophy-hunting.
0:39:46 > 0:39:51Both have affected the Marsh pride in the past and could do again.
0:39:56 > 0:40:02But, perhaps the biggest pressure on lion prides comes from the landscape in which they live.
0:40:04 > 0:40:11The landscape which Craig and his team have shown to be crucial to the evolution of the pride.
0:40:13 > 0:40:16By looking at the breeding success of known prides,
0:40:16 > 0:40:19the team discovered that those holding territories
0:40:19 > 0:40:21centred around river confluences
0:40:21 > 0:40:23were the largest and most successful.
0:40:29 > 0:40:35Territories that contain permanent water, shade and cover in which to raise cubs.
0:40:38 > 0:40:42Only powerful prides were able to defend these much sought-after territories
0:40:42 > 0:40:47from other lions and so ensure their long-term genetic success.
0:40:54 > 0:40:58It stands to reason then, that changes to the very driving force
0:40:58 > 0:41:03behind the evolution of lion prides would have a huge effect on their population.
0:41:05 > 0:41:10And there's no doubt the lion's landscape has changed dramatically in recent years.
0:41:13 > 0:41:19A striking example affects the lions of Tarangire National Park in Tanzania.
0:41:26 > 0:41:30The park covers nearly 1,000 square miles,
0:41:30 > 0:41:33bigger than the whole of the Mara.
0:41:35 > 0:41:40But unlike the Maasai Mara, which is connected to the vast Serengeti, Tarangire is isolated.
0:41:42 > 0:41:48A real problem for the park's population of approximately 200 lions.
0:41:52 > 0:41:58The park and the surrounding area is home to the Tarangire Lion Project
0:41:58 > 0:42:00and it's run by Bernard Kissui.
0:42:02 > 0:42:05One of Tanzania's most respected ecologists,
0:42:05 > 0:42:09he's noticed a big change in the landscape over the years.
0:42:09 > 0:42:16Traditionally here the indigenous people have always been the Maasai,
0:42:16 > 0:42:19and they are keeping livestock,
0:42:19 > 0:42:23but increasingly also we are seeing a slow change
0:42:23 > 0:42:28from pure livestock-keeping, pastoralism, to agro-pastoralism.
0:42:28 > 0:42:34So more and more people now need to you know keep some livestock but also, grow some crops.
0:42:38 > 0:42:45The increase in farmland outside the park is reducing the space for both lions and their natural prey.
0:42:47 > 0:42:52The park boundaries were drawn up in 1970, but over the course of Bernard's study
0:42:52 > 0:42:56he's discovered that about three quarters of the lions in the park
0:42:56 > 0:43:01actually leave its protection regularly throughout the year.
0:43:01 > 0:43:03And that brings them into danger.
0:43:06 > 0:43:11Lions go out, attack livestock, people retaliate.
0:43:11 > 0:43:15You know, they go out, find out where the lion is and kill it.
0:43:17 > 0:43:21Over the years, we have been collecting this information
0:43:21 > 0:43:23and you'll be surprised to hear
0:43:23 > 0:43:28more than 30 lions sometimes get killed every year.
0:43:30 > 0:43:33And that has got huge implications to the population.
0:43:35 > 0:43:39With a total population of just 200 lions in the park,
0:43:39 > 0:43:45having 30 of them killed in retaliation for livestock predation annually is significant.
0:43:54 > 0:43:58To stand even the remotest chance of maintaining lions in the park,
0:43:58 > 0:44:01Bernard had to win over the local community.
0:44:03 > 0:44:06THEY CONVERSE IN SWAHILI
0:44:08 > 0:44:15'We are now trying to convince the pastoralists keeping livestock to adopt new ways.
0:44:17 > 0:44:22'So, one of the things we're actually testing, is the use of chain-link fences.'
0:44:26 > 0:44:33Traditional cattle stockades, or "bomas" are, more usually constructed from thorn bushes
0:44:33 > 0:44:37but the chain-link fences offer better protection.
0:44:37 > 0:44:41We've been working on this particular strategy for about now two or three years.
0:44:41 > 0:44:48We have almost 60 bomas right now that have been enforced and we've been monitoring them.
0:44:51 > 0:44:54Where chain-link fencing has been installed,
0:44:54 > 0:44:57there's been no further instances of lions taking cattle.
0:44:57 > 0:45:01And hence the motivation for retaliation is lower.
0:45:07 > 0:45:14But changes to the landscape outside the park affect the lion population on a bigger scale.
0:45:16 > 0:45:22Reducing prime lion habitat and reducing the number of lions potentially to zero.
0:45:37 > 0:45:38Just as in Tarangire,
0:45:38 > 0:45:43for the Marsh pride, the changes outside the Mara reserve
0:45:43 > 0:45:46could have an effect on their success as a pride.
0:45:52 > 0:45:58The Marsh lions are a boundary pride, as I'd put it, because if you look at my map here you can see
0:45:58 > 0:46:02that the reserve boundary cuts through the top of their territory and that boundary
0:46:02 > 0:46:09is very close to here, it's just up the top there I can see cattle and Maasai just beyond it.
0:46:12 > 0:46:18The boundary to the Mara, like most national parks or reserves in Africa, isn't marked by fences
0:46:18 > 0:46:23and the area beyond it has changed dramatically in my time watching this pride.
0:46:25 > 0:46:31The Maasai population here has grown enormously in the last 30 years.
0:46:35 > 0:46:39But, unlike in Tarangire,
0:46:39 > 0:46:44the Marsh pride are bordered on just one side by an increasing human population.
0:46:46 > 0:46:53The Mara reserve is part of the much more extensive Serengeti Mara system.
0:46:53 > 0:46:54And this is critical.
0:46:56 > 0:47:03It's one of the six large areas that Craig Packer believes might be the last stronghold of the lion.
0:47:05 > 0:47:09It's so large that the migration of two million wildebeest
0:47:09 > 0:47:11can be completed entirely within it.
0:47:19 > 0:47:24And the migration brings other animals too.
0:47:26 > 0:47:31Nomadic male lions in search of their own pride follow the herds.
0:47:33 > 0:47:36Lions that could bring new diseases.
0:47:36 > 0:47:42Or in taking over an existing pride, cause the death of young cubs.
0:47:48 > 0:47:52For now, the Marsh males still control their territory.
0:47:54 > 0:47:59And, at least in Romeo's case, still actively attempting to sire new offspring.
0:48:03 > 0:48:07Clawed, in his poor condition, can only watch from a distance.
0:48:17 > 0:48:22For male lions life is a race against the inevitable.
0:48:25 > 0:48:28Their time as a pride male is limited.
0:48:28 > 0:48:32And they need to make hay while the sun shines.
0:48:35 > 0:48:38They will, ultimately, be challenged.
0:48:38 > 0:48:42Challenged by new males from far and wide.
0:48:46 > 0:48:53The consequences of new males taking over a pride can be catastrophic in the short-term.
0:48:56 > 0:49:01But it's a vital part of a healthy lion population, mixing the gene pool.
0:49:01 > 0:49:07The situation without an influx of new males is far worse in the long-term.
0:49:16 > 0:49:21It's a situation faced by the lions of Tanzania's Ngorongoro Crater.
0:49:29 > 0:49:33The area for which Craig and his team have the most lion data.
0:49:36 > 0:49:40I travelled with Craig into this vast volcanic caldera.
0:49:47 > 0:49:50It's one of the lion hot-spots of East Africa.
0:49:54 > 0:49:58The prey here is resident all year round
0:49:58 > 0:50:04and this natural cauldron once supported the highest density of lions anywhere in Africa.
0:50:08 > 0:50:10But not any more.
0:50:12 > 0:50:15It's a direct result of the lack of new males
0:50:15 > 0:50:19able to enter the crater from areas outside.
0:50:19 > 0:50:22In 1959, there were 8,000 people that lived in the Ngorongoro
0:50:22 > 0:50:27conservation area and now there are 60,000.
0:50:27 > 0:50:30There's just so many Maasai in close proximity around the wall
0:50:30 > 0:50:32that there's a barrier to migration.
0:50:34 > 0:50:38Now we have had a series of disease outbreaks the last few years,
0:50:38 > 0:50:41the lions seem more susceptible to disease than before,
0:50:41 > 0:50:48and ordinarily we'd expect males to come in to help repopulate. No longer.
0:50:51 > 0:50:56This lack of new males has led to a reduction in genetic diversity
0:50:56 > 0:50:59amongst the lion population on the Crater floor.
0:50:59 > 0:51:03A result of narrow inbreeding between the lions that remain.
0:51:16 > 0:51:17So who are we looking at here?
0:51:17 > 0:51:21Well, this female comes from the Mungi pride.
0:51:21 > 0:51:24The male comes from the other side of the Crater floor
0:51:24 > 0:51:27and even though he didn't know her growing up
0:51:27 > 0:51:30they do have many links on their family tree,
0:51:30 > 0:51:34so they're about as closely related as half-siblings.
0:51:43 > 0:51:49But as lions to look at the effect of this inbreeding isn't immediately obvious.
0:51:49 > 0:51:51When I look at these lions,
0:51:51 > 0:51:53I'm looking at healthy, vigorous animals,
0:51:53 > 0:51:56I mean that's a big male, the female looks in great shape,
0:51:56 > 0:52:01so really, how much impact is inbreeding having on these lions?
0:52:01 > 0:52:04They look great, but they get such a high level of nutrition
0:52:04 > 0:52:07down here, there's always food available for them.
0:52:07 > 0:52:11The things that are harming them are all happening inside their bodies.
0:52:15 > 0:52:18We're seeing signs, and have seen for some time,
0:52:18 > 0:52:22of reduced fertility in the males, they have higher levels
0:52:22 > 0:52:26of sperm abnormality, they have lower testosterone
0:52:26 > 0:52:28and their immune systems seem to be compromised now.
0:52:28 > 0:52:33This population seems to be exceptionally sensitive to infectious disease.
0:52:35 > 0:52:38From a high of 120 lions in the 1980s,
0:52:38 > 0:52:43the Crater population today numbers less than 60.
0:52:47 > 0:52:52Ngorongoro reveals the problems for lions in small populations.
0:52:54 > 0:52:58If lions are to survive here they'll need human management,
0:52:58 > 0:53:02introducing new lions with new genes.
0:53:05 > 0:53:11But this is difficult - lion prides don't tolerate outsiders.
0:53:11 > 0:53:15The financial cost is large and only for small, valuable populations
0:53:15 > 0:53:19like the Crater, where tourists expect to see lions
0:53:19 > 0:53:22will it be cost-effective to manage so intensively.
0:53:39 > 0:53:41The Marsh pride are, for now,
0:53:41 > 0:53:47thankfully still part of a much larger, natural, lion population.
0:53:47 > 0:53:49That of the Mara Serengeti system -
0:53:49 > 0:53:53perhaps the world's most famous African reserves.
0:54:01 > 0:54:05This journey has shown me how fortunate I've been
0:54:05 > 0:54:09in being able to watch this one pride for so many years.
0:54:13 > 0:54:15From my own experience,
0:54:15 > 0:54:18their immediate future can almost be predicted.
0:54:23 > 0:54:26As the wildebeest migration heads south, there'll be less prey,
0:54:26 > 0:54:31resulting in more competition within the pride for food.
0:54:35 > 0:54:40Clawed is likely to lose out and his condition will worsen.
0:54:42 > 0:54:47But his, and buddy Romeo's success has already been assured
0:54:47 > 0:54:51in the form of their nine almost fully-grown offspring.
0:54:54 > 0:54:59New males in the area will challenge this ageing pair
0:54:59 > 0:55:02and ultimately win.
0:55:02 > 0:55:04Just how soon they do
0:55:04 > 0:55:08will decide the fate of the youngest cubs in the pride.
0:55:08 > 0:55:12A new chapter in the Marsh pride's story will begin.
0:55:15 > 0:55:19But the lion's story as a whole may be closer to an end
0:55:19 > 0:55:21than I'd previously imagined.
0:55:23 > 0:55:27I think the animal is close to being restricted
0:55:27 > 0:55:30to maybe three or four places.
0:55:31 > 0:55:33The Serengeti is so famous,
0:55:33 > 0:55:36it's hard to believe that anyone will let that die,
0:55:36 > 0:55:38parts of the Selous can be protected,
0:55:38 > 0:55:42Kruger National Park in South Africa is fenced.
0:55:42 > 0:55:45The Okavango is in the middle of a desert,
0:55:45 > 0:55:50so those four areas maybe the sole repository of healthy lions
0:55:50 > 0:55:52in the 22nd century.
0:56:04 > 0:56:10It's a stark situation for an animal whose success once rivalled our own -
0:56:10 > 0:56:13the seconnd most widespread land mammal on Earth.
0:56:16 > 0:56:20For lions, social living has made them especially vulnerable
0:56:20 > 0:56:23to disease spread from our domestic animals.
0:56:23 > 0:56:28Hunting individual male lions for trophies can all too easily
0:56:28 > 0:56:32have devastating impacts on entire prides.
0:56:32 > 0:56:34GUNSHOT ECHOES
0:56:35 > 0:56:39And as territory is key to the lion's social way of life,
0:56:39 > 0:56:43it's becoming obvious that healthy lion populations
0:56:43 > 0:56:48can only exist where large areas of suitable habitat can be found.
0:56:51 > 0:56:56Habitat that, throughout our long association with the lion,
0:56:56 > 0:56:59has also been coveted by humans.
0:56:59 > 0:57:04But, living with this large, dangerous, social predator
0:57:04 > 0:57:07has been difficult and still is.
0:57:07 > 0:57:09Everybody hates lions.
0:57:09 > 0:57:13Pastoralists hate lions, people in man-eating areas
0:57:13 > 0:57:17would just as soon there were never any more lions ever again.
0:57:17 > 0:57:22And I often find it surprising that we somehow expect Africa
0:57:22 > 0:57:27to bear the brunt of living with a really difficult species.
0:57:27 > 0:57:30Seems to me that's the world's responsibility.
0:57:30 > 0:57:34If the lion was lost, that's something that belongs to all of us,
0:57:34 > 0:57:36it's part of our whole history.
0:57:45 > 0:57:47There's a big irony here.
0:57:48 > 0:57:52The lion's uniquely social way of life, which to me makes them
0:57:52 > 0:57:58so fascinating, evolved as a defence against others of their own kind.
0:58:06 > 0:58:13But the truth about lions is that their biggest threat is no longer other lions...
0:58:13 > 0:58:15it's us.
0:58:27 > 0:58:30Subtitles by Red Bee Media Ltd
0:58:30 > 0:58:33E-mail: subtitling@bbc.co.uk